1. Field of the Invention
This invention relates to the field of brushes, and more particularly to an improved angled bristle array configuration in a rotary brush assembly of the type used in vacuum cleaners.
2. Description of the Prior Art
The use of rotary brush assemblies in cleaning apparatus such as vacuum cleaners is well known. Rotary brush assemblies have included a generally cylindrical brush roller body carrying on its outer surface an array of radially extending tufted bristles. The roller body is mounted on the vacuum cleaner for powered sweeping rotation, to loosen debris to facilitate its removal by appropriate air flow. Beater bars are sometimes also attached to the roller body to enhance cleaning efficiency. The bristle array and beater bars are distributed regularly about the periphery of the roller body to balance the moments of inertia about the roller body axis.
An example of a prior art rotary brush assembly is described in U.S. Pat. No. 3,874,017, issued on Apr. 1, 1975 to Russel H. R. Parker, and assigned to the present Assignee. This patent is expressly incorporated by reference here.
One form of known rotary brush assembly includes a brush roller having several helical rows of bristle tufts distributed on its periphery. In such an assembly, the bristles extend outwardly from the brush roller substantially perpendicular to the roller axis. It has been proposed that alternate rows of bristles about the roller circumference comprise bristles having differing degrees of stiffness. For example, one proposal is to use alternate rows of horse and goat hair.
It has also been proposed to drill holes in the outside surface of a wooden cylindrical roller body at differing angles with respect to its axis. Identical bristle tufts were then inserted in the various holes and fastened therein with wire staples or the like. In such an assembly, in order to achieve a wider sweeping range and to improve edge cleaning capability, it has been proposed that the end bristle tufts near the roller body ends be angled outwardly.
Such rotary brush assemblies have exhibited undesirable nonuniformity in sweeping efficiency along the length of the assembly.
Such assemblies have included the use of somewhat longer bristles for the more angled tufts than in those which are more closely perpendicular to the roller body axis. Such an arrangement provides equal bristle extension from the roller body axis. Residual sweeping nonuniformity remained, because the longer, more angled, bristles were less stiff than the shorter, less angled ones.
It is thus an object of this invention to provide a rotary brush assembly having advantages of appropriately angled bristle tufting without disadvantages of nonuniform sweeping action.